Why do many cars nowadays have no amber rear-turn signals?

Most cars nowadays have amber rear-turn signals are hidden either within the red (stop light or back night lamp) or white (reverse drive) signals, or just replaced by the red.

Why do automakers nowadays do that, and why don’t they care about those?
Did the amber lights bother? Or is it more modern-looking?

They were mainly used in cars made in the 1990s through the early 2000s, and now barely any new car has those amber lights.

Here’s a list of what new cars I know still have amber rear-turn signals:

Kia Soul
Nissan Altima
Nissan Murano

The Toyota Corolla and Highlander had facelifts for the 2011 model year that eliminated those amber rear-turn signals. The Corolla looks way TOO much like the pre-facelift Mazda6.
(If only that facelift didn’t happen, it would be good)

I also know that a while ago, the Mazda3 had amber rear-turn signals, but when the 2nd generation came, they removed those.

So… Why do automakers nowadays decide to remove amber rear-turn signals from their cars?
Is there a law or something?